SENER Aeroespacial has successfully completed the acceptance tests of the flight model of the magnetometer boom for the Jupiter Icy Moons Explorer mission (JUICE). Juice is a program of the European Space Agency (ESA) designed to expand our knowledge of the complex interactions between Jupiter and its icy moons: Europe, Callisto and Ganymede. It is scheduled to be launched in 2022.

SENER Aeroespacial was responsible for the design, manufacturing, verification and integration of the magnetometer boom, the purpose of which is to place some of the instruments required for the scientific experiments away from the spacecraft in order to prevent magnetic interference. Once deployed, its length is 10.6 m being the longest boom made for an ESA project to date. It will carry five instrument sensors that are needed to perform two characterization experiments, one for the internal magnetic field of Ganymede, called J-MAG, and the other for the subsurface oceans of the icy moons, called RPWI.

In addition to its length, the design of the boom is driven by some extremely demanding requirements, such as the temperature range and radiation levels to which it will be subjected, required magnetic cleanliness to avoid disturbing the magnetometer measurements, the mass constraint, etc.

We should note that SENER Aeroespacial has also developed three other projects for JUICE: the medium-gain antenna subsystem (MGAMA), which includes the antenna reflector, the pointing mechanism and the control electronics; the design and manufacture of a series of Mechanical Ground Support Equipment (MGSE) for the assembly and testing of the satellite's solar panels; and the Filter Wheel Module (FWM) of the JANUS instrument, a high-performance camera to research Ganymede, Europa and Callisto and the Jovian system.Acceptance test campaign of the boom

The tasks to verify the boom began by testing the various subsystems individually: deployment mechanisms, Hold-Down and Release Mechanisms (HDRM) and the bonded joints between the carbon fiber reinforced plastic and metal parts. These subsystems are checked first, since the final size of the product is too large for functional checks in climatic and vacuum chambers at operational temperatures.

Once these tests were completed, the full system - together with the instruments harness mounted on the boom, which was provided by the client - was integrated at SENER Aeroespacial's facilities in Asúa (Vizcaya, Spain). Finally, the assembly was verified at the facilities of the European Space Research and Technology Centre (ESTEC) in Noordwijk, the Netherlands.

The system simultaneously deploys the three segments that comprise the boom. These segments are each driven by an independent deployment mechanism. The deployment speed is controlled by a viscous damper located in the satellite interface mechanism, while the other two are controlled using a system of pulleys and retaining cables. The functional test was carried out using three helium balloons, each of which supported the weight of a segment of the boom from its center of gravity, thus, simulating the zero gravity condition for which the system is designed to operate.

The video above shows one of the deployment tests carried out at ESTEC, which was intended to verify the proper operation of the boom after the dynamic launch tests. Once the last HDRM is activated, the boom deploys freely, controlled by the viscous damper and supported by the three balloons.